Route reliability record
IAH→LAS
Houston to Las Vegas
- Flights
- 3,409
- Period
- September 2025 to August 2026
- Distance
- 1,222 mi
- Carriers
- 3
This route lands a B+, 6 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That rests on 3,409 IAH to LAS flights, of which United Airlines flew 2,598 at 85.2% on time.
Best time to fly IAH to LAS: a 5am–8am departure, ideally on a Wednesday. Flights in that window arrived on time 94.0% of the time and Wednesday flights 91.4%, against 82.8% for the route overall.
United Airlines is the most reliable of the three carriers covered here at 85.2% on time across 2,598 flights.
Key figures
On time
82.8%
Arrivals under 15 minutes late, of 3,376 completed flights
Avg delay
71 min
Across delayed arrivals only, not all flights
Cancelled
0.85%
National rate is 1.89%
Best carrier
United
85.2% on time across 2,598 flights
These figures cover 3,409 flights between September 2025 and August 2026. The median arrival is 11 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
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Carrier by carrier
Which airline is most reliable on IAH to LAS
The choice of carrier is not cosmetic here. United Airlines arrives on time 85.2% of the time; Frontier Airlines manages 70.1%. Sample sizes sit next to every figure, because a two-point gap across 410 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 2,598 | 85.2% | 60 min | 0.27% | A+ |
| Spirit Airlines | 401 | 80.3% | 75 min | 2.49% | B |
| Frontier Airlines | 410 | 70.1% | 105 min | 2.93% | C |
The spread between United and Frontier is 15 points, wide enough that it should decide the booking. On a hundred trips that is 15 more arrivals inside the on-time window.
Flight by flight
Flights on IAH to LAS
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly Houston to Las Vegas
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 1 of the top 4 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. IAH → LASHouston to Las Vegas | United Airlines | 85.0% | 85.2% | 0.27% | 5am–8am, Wed | UA 1264 07:35 |
| 2. HOU → LASHouston to Las Vegas | Southwest Airlines | 79.5% | 79.8% | 0.35% | 5am–8am, Wed | — |
| 3. IAH → LASHouston to Las Vegas | Spirit Airlines | 78.3% | 80.3% | 2.49% | 5am–8am, Wed | — |
| 4. IAH → LASHouston to Las Vegas | Frontier Airlines | 68.0% | 70.1% | 2.93% | 2pm–5pm, Wed | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 20 points, against 15 points between the best and worst carrier.
- 5am–8am369 flights94.0%
- 8am–11am455 flights87.5%
- 11am–2pm566 flights85.9%
- 2pm–5pm714 flights84.0%
- 5pm–8pm561 flights79.1%
- 8pm–5am744 flights73.6%
Scale runs 65% to 100%.
Book the early departure. Flights leaving between 5am–8am arrive on time 94.0% of the time, against 73.6% for the overnight window. That is 20 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 744 flights scheduled in it.
Explore
Filter IAH to LAS by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On IAH to LAS, the best departure window is 5am–8am at 94.0% on time and the worst is 8pm–5am at 73.6%, a wide gap of 20.4 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am94.0%
- 8–11am87.5%
- 11am–2pm85.9%
- 2–5pm84.0%
- 5–8pm79.1%
- 8pm–5am73.6%
best all US flightsScale 60% to 100%.
Across the year
When delays peak on this route
This route's year swings by 17 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
June is the worst month at 73.9% on time, 17 points below February, the best at 90.9%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. March was the busiest month here, with 323 flights.
Across the week, Wednesday is the strongest day at 91.4% on time and Friday the weakest at 77.5%, a spread of 14 points.
Delay causes
Why this route gets delayed
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 41,000 reported delay minutes.
- 39%Late-arriving aircraft
- 35%Carrier
- 23%National Airspace System
- 3%Extreme weather
- 0%Security
39% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 41,000 reported delay minutes here, that single category outweighs weather by 14 to one. The split is drawn from 41,180 reported delay minutes.
The largest share of delay minutes, 35%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 14,000 of the 41,000 delay minutes reported here.
Cancellations are rare at 0.85%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here actually costs
6.4% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last a little over an hour, which a normal layover absorbs.
The 1,222 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
The return leg runs 84.2% on time across 3,411 flights, within about a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 3,409 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in LAS after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. February runs 90.9% on time and June 73.9%, a swing of 17 points. If the dates move at all, move them out of June before you think about anything else. 3,376 completed flights over 12 months sit behind that.
Common questions
IAH to LAS questions
How often is IAH to LAS delayed?
About one flight in six arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 17.2% of the 3,409 flights in this analysis, against 22.7% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on IAH to LAS?
United Airlines leads at 85.2% on time across 2,598 flights. Frontier Airlines is at the other end on 70.1%, a gap of 15 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on IAH to LAS?
The 5am–8am departure window is the strongest at 94.0% on time. The 8pm–5am window is the weakest at 73.6%, 20 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are June delays on IAH to LAS?
June is the weakest month at 73.9% on time, compared with 90.9% in February. Across the year that is 17 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- LAS to IAH — the return legseparate record
- George Bush Intercontinental (IAH) delay statistics
- Harry Reid International (LAS) delay statistics
- United Airlines on IAH to LAS85.2%
- Spirit Airlines on IAH to LAS80.3%
- Frontier Airlines on IAH to LAS70.1%
- IAH to ORD, a related route75.1%
- LAX to LAS, a related route75.8%
- IAH to DFW, a related route76.4%
- United Airlines on-time record85.2%
- Spirit Airlines on-time record80.3%
- Frontier Airlines on-time record70.1%
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
Direction matters. IAH to LAS and LAS to IAH are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.